The method according to the present invention relates to the art of automatic control in power engineering and more particularly to automatic control of active power distribution in power transmission lines.
Several principles of effecting automatic control of power distribution in power transmission lines are known in the art, such as, for example, a control system implemented in the network coupling the Krasnoyarsk system to the joint power system of Western Siberia. A characteristic feature of this and other similar systems resides in the fact that 1) in case the deviation of the controlled power flow from the mean value is comparatively small, the power flow being distributed not exceeding the set value of the limiter, the power flow is integrally controlled at a rather low rate, whereas 2) if the deviation of the controlled power flow from the mean value is so great that the distributed power flow exceeds the set value of the limiter, a high-speed proportional-plus-integral control is effected at a very high rate.
A disadvantage of the above principle of control is that a fast (proportional-plus-integral) control is carried out all the time the distributed power flow exceeds the value of the limiter setting, without taking into consideration the fact that almost any deviation of the distributed power flow which reaches the value of the limiter setting is likely to exceed, during the ensuing period of time, the limit of power that is being distributed along a given transmission line, which limit is selected with the aim of ensuring a stable parallel operation of the power system or preventing thermal overload of the line. In the case under consideration, the control system is bound to run idle most of the time, inasmuch as there frequently occur such power flow deviations that, while exceeding the value of limiter setting, do not cause any line overload. The result is that the overall capacity of the power transmission line is not used to the full extent when it is required to transmit a heavy power flow. Moreover, it tends to increase the costs and impair the reliability of operation of the power stations engaged in distributing the flows of power, said power stations being forced to operate overtime under the undesirable conditions of rapidly varying loads.